脂肪因子CTRP1致动脉粥样硬化及机制研究

C1q/TNF-related protein (CTRP), a novel adipokine family, is closely related to cardiovascular diseases. Among the family members, CTRP1 has been shown to be involved in inflammatory reaction and increased vascular stress. In the present study, CTRP1 level has been shown to be significantly increased in severe atherosclerotic tissue than in non-atherosclerotic tissue, and serum level of CTRP1 is remarkably higher in patients with coronary artery disease as compared with controls. In vitro experiments, inflammatory factors induce CTRP1 production in HUVEC and THP-1 cells, and recombinant CTRP1 protein causes expression of adhesion molecules (VCAM-1 and ICAM-1) in endothelial cells. Moreover, CTRP1 prtein promotes adhesion of monocytoid cells to endothelial cells and of leukocytes to the wall of mesenteric venules, observed by intravital microscope. We have also shown that CTRP1 binds receptor for advanced glycation end-products (RAGE) and toll-like receptor-4 (TLR-4), suggesting that CTRP1exerts atherogenic effects via RAGE and TLR-4 signaling pathways. Next, we will evaluate whether CTRP1 cause atherosclerosis using apoE-KO mice with peritoneal injection of recombinant CTRP1 and adenoviral CTRP1 particles, and apoE-KO/CTRP1-KO mice, and also assess whether the effects of CTRP1 are mediated by RAGE and TLR-4 using apoE-KO/RAGE-KO and apoE-KO/TLR-4-KO mice. The mechanisms regarding pathogenesis of CTRP1 will be clarified.

脂肪因子CTRP(C1q/TNF-related protein)家族与心血管疾病有关。根据文献，CTRP1参与炎症和血管张力增高机制。我们发现，动脉粥样硬化血管组织中CTRP1水平比非病变血管显著升高；冠心病患者血清CTRP1水平高于对照。炎症因子诱导内皮和巨噬细胞表达CTRP1； CTRP1促粘附分子表达，诱导单核细胞对内皮细胞粘附和白细胞对肠系膜小血管壁粘附；并且CTRP1与终末糖化产物受体(RAGE)和Toll样受体(TLR)-4结合。提示CTRP1经RAGE和TLR-4介导促进动脉粥样硬化。后续将用腹腔注射CTRP1蛋白和腺病毒CTRP1的apoE-KO、apoE-KO/CTRP1-KO小鼠明确CTRP1促动脉粥样硬化作用；用apoE-KO/RAGE-KO和apoE-KO/TLR-4-KO小鼠验证CTRP1致病是否需RAGE和TLR-4介导。以体内体外实验阐明CTRP1致病机制。

CTRP（C1q TNF-related protein）1是CTRP家族的重要成员，在脂肪组织含量多，在血管壁组织中也有表达。该脂肪因子家族与炎症、免疫调控关系密切。但CTRP1是否与动脉粥样硬化有关还不清楚。本研究①探讨了CTRP1与冠心病发生及其严重度的关系；②在体内和体外实验中，研究CTRP1对细胞、血管病理和高脂饲养小鼠动脉粥样硬化模型的影响；③在体内和体外实验中，探讨CTRP1对血管生物学的影响。我们的研究结果显示：①发现动脉粥样硬化血管和冠心病患者血清中、外周血单个核细胞中CTRP1较非动脉粥样硬化对照组织、细胞和正常人血清显著增高。病理检查发现，严重动脉粥样硬化血管斑块中CTRP1表达较非动脉粥样硬化对照组织明显增高，并与巨噬细胞CD68共定位。②体外实验中，CTRP1重组蛋白促进动脉内皮细胞和巨噬细胞炎症反应。③在C57Bl/6、CTRP1-/-、apoE-/-和apoE-/-/CTRP1-/-双敲等小鼠体内研究中发现CTRP1具促动脉粥样硬化作用，而CTRP-/-小鼠体内炎症和动脉粥样硬化明显减弱。④用在体小鼠提睾肌动脉舒张功能实验和体外血管环舒张实验中，发现CTRP1能显著抑制动脉的舒张功能。CTRP1使小鼠提睾肌动脉组织中NO含量明显降低，而使氧化应激ROS水平显著上升。运用ROS抑制剂能显著改善CTRP1产生的影响。⑤CTRP1能量效依赖性和时间依赖性地上调精氨酸酶1，而精氨酸酶2则没有明显改变。我们用精氨酸酶抑制剂nor-NOHA则可逆转CTRP1产生的对血管舒张的抑制作用。这些结果说明脂肪因子CTRP1异常增高有促动脉粥样硬化作用，同时还有影响了血管的舒张功能。因此，有效干预CTRP1异常增高所带来的致病效应是很一个重要环节。本研究的发现具有原创性，已在本领域主流杂志上发表。